BOLL & KIRCH

Duplex Filter

Advantages of the duplex strainers

During normal operations the strengths of the duplex filter is that it can be completely operated maintenance-free, except for checking the seals and cleaning of the filter element. With two filter chambers connected with a changeover valve one chamber is always in operation while a clean filter chamber is in standby mode.  Duplex filters are primarily used where shutting down machines and systems are not practical or highly uneconomical, for example, in the maritime or the production industry.

How the duplex strainer works:

Filtration phase

While one filter chamber of the duplex strainer is in filtering mode, the other chamber is always with a cleaned filter element off line. The liquid passes through the filter element and over time the pressure drop in this filter chamber will increase. The increased pressure drop is an indication that particles have been accumulated and cleaning is required. Optional a differential pressure indicator can be installed on the duplex strainer.

Cleaning phase

By activating the switch plug, the clean filter chamber will be put in operation and the dirty filter chamber is simultaneously switched off. Switching to the clean filter chamber is carried out without a pressure surge.

For cleaning, the contaminated filter chamber is depressurized by the vent screw, the housing cover is
removed and the filter element has to be removed. The filter element is cleaned by flushing it with a cleaning fluid and subsequently blown out using compressed air.

Duplex Filter

BOLLFILTER Duplex Type 2.04.5

BOLLFILTER Duplex Type 2.04.5
Flange Connection
DIN Only DN 25 - DN 80 (Approx. 1" - 3")
Switch-over
cock valve
Filter element
star-pleated element, basket element
more information

BOLLFILTER Duplex Type 2.05.5

BOLLFILTER Duplex Type 2.05.5
Flange Connection
DIN Only DN 100 - DN 250 (Approx. 4" - 10")
Switch-over
cock valve
Filter element
basket element, ring element, filter candle insert, multi-mantle element
more information

BOLLFILTER Duplex Type 2.68.2 / 2.78.2

BOLLFILTER Duplex Type 2.68.2 / 2.78.2
Flange Connection
ASME or DIN 2 ½" - 14" DN 65 - DN 350
Switch-over
ball valve Change over (optional as with Butterfly valves)
Filter element
cleanable (stainless steel element), disposable (glass-fiber matting)
more information

BOLLFILTER Duplex Type BFD

BOLLFILTER Duplex Type BFD
Flange Connection
ASME or DIN 1" - 6" / DN 25- DN 150
Switch-over
ball valve
Filter element
candle or basket element
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BOLLFILTER Duplex Type BFD-P HD

BOLLFILTER Duplex Type BFD-P HD
Flange Connection
ASME or DIN ¾” – 8” or DN 20 – DN 200
Filter element
Fiberglass/stainless steel disposable cartridges* Cleanable elements (star-pleated) made of stainless steel
Grade of filtration
0,5 - 250 µm
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BOLLFILTER Duplex Type BFD-C HD

BOLLFILTER Duplex Type BFD-C HD
Features
Duplex filter for separating solids and aerosols (liquid content) from gases
Flange Connection
ASME or DIN ¾” – 8” or DN 20 – DN 200
Filter element
Fiberglass/stainless steel disposable cartridges (as normal temperature and high/low temperature design); Option available for preliminary separation using demister, cyclone, or cyclone demister all within the same housing.
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BOLLFILTER Duplex BFD-C/P Double Block and Bleed

BOLLFILTER Duplex BFD-C/P Double Block and Bleed
Features
A special design duplex filter for separating solids and/or aerosols (liquid content) from gases using a patented double block and bleed main transfer valve. This is intended for applications using high pressures and/or dangerous gas compositions, to ensure maximum operator safety.
Flange Connection
ASME or DIN ¾” – 8” or DN 20 – DN 200
Filter element
Fiberglass/stainless steel disposable cartridges* Option available for preliminary separation using demister, cyclone, or cyclone demister all within the same housing
more information